The subject invention relates to an improved electrical utility service tester that is used for troubleshooting 120/208 or 120/240, three-phase or single-phase alternating current electrical utility services where 120 volt hot legs of the electrical utility services are connected 120 volts to ground only. The tester is self-contained in a weatherproof case, which enables the tester to withstand exposure to adverse weather conditions without damage or loss of function. The tester also includes circuitry for preventing damage to the electrical circuitry of the tester by preventing the test circuitry for the left and right hot legs of a circuit under test from being simultaneously operative and the test load circuitry for intermittent and continuous test load application from being simultaneously operative.
An electrical utility service tester is typically utilized by an electrical technician to troubleshoot the electrical utility service being provided to a customer by connecting the tester to the customers service meter and running tests and, where electrical service is being provided to two or more customers from a transformer, to determine which power line at the transformer is supplying electrical service to a particular customer. When running tests on an electrical utility service to troubleshoot that service, the electrical utility service tester is used to determine whether or not the left and right hot legs of the service are shorted together; whether or not there is at least a total of 130 to 135 volts being provided by the service; whether or not the neutral leg of the service is defective; whether or not the left hot leg of the service is defective; and whether or not the right hot leg of the service is defective.
Part of the testing provided by these electrical utility service testers for testing the neutral leg, the left hot leg, and the right hot leg of a electrical utility service involves measuring the potential between the left hot leg and the neutral leg of a service under test and measuring the potential between the right hot leg and the neutral leg of a service under test. Should the test circuitry for measuring the left leg potential and the right leg potential of a service under test be operative simultaneously, even briefly, a power surge is created through a portion of the tester circuitry that can severely damage the tester circuitry.
Previous, electrical utility service testers have utilized a rocker switch for controlling the test circuitry of these testers for testing the neutral leg, the left hot leg, and the right hot leg of the electrical utility service. The rocker switch of these testers has a first off position where the test circuitry for both hot legs is turned off; a second position for turning on the test circuitry for testing the left hot leg potential; and a third position for turning on the test circuitry for testing the right hot leg potential with the first off position of the switch being intermediate the second left hot leg test circuitry on position and the third right hot leg test circuitry on position. The test circuitry of these testers for testing the neutral leg, the left leg, and the right hot leg of the electrical utility service includes relays for closing and opening the different circuits of the tester. When the test circuitry of the tester for including either the left hot leg or the right hot leg of the service in a test is turned off by the rocker switch the inclusion of these relays in the test circuitry causes a delay in the opening of the circuit being turned off. Thus, once a test including either the left or right hot leg of a service has been initiated on one of these previous testers by actuating the rocker switch to either the left or right hot leg test on position and the technician desires to test the other hot leg of the service, the rocker switch on these testers should first be returned to the intermediate off position and then, after a pause to allow the previously actuated test circuit of the tester to open, moved to the on position for closing and initiating a test with the circuitry of the tester for the other hot leg of the service. Otherwise, the test circuitry of the tester for measuring the left leg potential and the right leg potential of a service under test can become operative simultaneously thereby creating a power surge through a portion of the tester circuitry that can severely damage the tester circuitry and make the tester inoperative. As a result of the need to properly operate these previous electrical utility service testers, the careless and improper operation of these previous electrical utility service testers by a technician who attempts to rapidly change the operation of the tester from one test circuit to the other, e.g. by jabbing at the switch so that the switch moves rapidly through the off position to the on position for the other test circuit, can severely damage these testers and there has been a need to provide an electrical utility service tester where the simultaneous activation of these test circuits can not occur.
The improved electrical utility service tester of the subject invention provides the industry with an electrical utility service tester that performs all of the testing functions of previous electrical utility testers, but wherein the simultaneous activation of the test circuits to perform these functions cannot occur to damage the circuitry of the tester. In addition, the improved electrically utility service tester of the subject invention includes a weatherproof casing that protects the circuitry of the tester from adverse weather conditions so that the tester of the subject invention can withstand exposure to adverse weather conditions without damage or loss of function.